Embodiments of this invention relate generally to methods of making cellulosic animal litters and, more particularly, to methods of making clumping cellulosic animal litters.
Small domesticated animals, such as cats, are often trained to urinate and defecate in special containers commonly referred to as litter boxes. Untrained caged animals, such as guinea pigs, hamsters, gerbils, dogs, birds, monkeys, ferrets and laboratory mice and rats urinate and defecate on the floors of their cages. Therefore, pet owners, veterinarians and laboratory personnel line the bottoms of litter boxes and cages with absorbent material to collect the animals' urine and feces. In order to control objectionable odors from the contaminated absorbent material, it is necessary to periodically remove and dispose of that material and to replace it with fresh absorbent material.
Until recently, it was found to be necessary to completely remove contaminated absorbent material from the litter boxes and cages in order to control objectionable odors. However, clay-based absorbent materials have been developed which, when wetted with animal urine, form coherent clumps that may be easily segregated and removed from the remaining uncontaminated absorbent material. These clay-based absorbents, which are generally referred to as “clumping litters”, are more efficient and convenient to use than prior absorbent materials. As a result, they have gained widespread commercial acceptance.
Unfortunately, clay-based absorbents have drawbacks. First, they are dusty. Second, clump formation in clay-based clumping litters is often not as rapid as be desired. Also, the clumps formed are often soft and friable, which can complicate their removal. Additionally, clay-based clumping litters are relatively expensive since they require that the clay be mined, processed, and often shipped long distances before being used to make clumping litters. The mining process is not only expensive, it can scar the landscape and is therefore environmentally undesirable.
Substrates containing at least 10% by weight cellulosic content are a known alternative to straight clay-based absorbents for use in absorbing and disposing of animal urine and feces. When such cellulosic materials are made from waste produced in paper manufacture, they offer significant advantages over clay-based absorbents. First, the starting material is very inexpensive. Second, it is plentifully available and, once used and disposed of the cellulosic component readily degrades, reducing disposal problems inherent in the use of clay-based absorbents. Some particularly desirable methods of making cellulosic granules or particles from paper waste are described in U.S. Pat. Nos. 4,560,527, 4,619,862, 4,621,011, and 4,721,059, the disclosures of which are incorporated herein by reference.
Although untreated cellulosic granules may form friable clumps, until the advent of the present embodiments, the only practical methods for making reliable and efficient clumping cellulosic absorbents are described in U.S. Pat. Nos. 5,970,916 and 6,662,749 to the present inventors. Although the clumping cellulosic litters of the '916 and '749 patents work well, it is desirable to improve the methods for making clumping cellulosic litters in accordance with the '749 patent.